Astronomers observe the awakening of a supermassive black hole for the first time

Sign up for CNN’s Wonder Theory science newsletter. Explore the universe with news about fascinating discoveries, scientific breakthroughs and more.

Astronomers are witnessing a spectacle never before seen in the cosmos: the awakening of a supermassive black hole at the center of a distant galaxy.

In late 2019, a team of astronomers noticed an otherwise normal galaxy called SDSS1335+0728, 300 million light-years away in the constellation Virgo. A sudden increase in the galaxy’s brightness was automatically detected by the Zwicky Transient Facility telescope at the Palomar Observatory in California.

With its extremely wide-field view, the camera scans the entire northern sky every two days, capturing data on celestial objects such as near-Earth asteroids as well as bright, distant supernovae.

An interdisciplinary team of astronomers and engineers followed Zwicky’s observation using information from space-based and ground-based telescopes to see how the galaxy’s luminosity has changed over time.

To their surprise, researchers realized they were witnessing a unique moment when a cosmic monster awakened. The results of the study were accepted for publication in the journal Astronomy & Astrophysics.

“Imagine that you have been observing a distant galaxy for years and it has always seemed calm and inactive,” said study lead author Paula Sánchez Sáez, an astronomer at the European Southern Observatory in Germany, in a statement. “Suddenly, its (core) starts to show dramatic changes in brightness, unlike any typical event we have seen before.”

The team classified the galaxy as having an active galactic nucleus, or a bright, compact region powered by a supermassive black hole.

Various celestial scenarios can cause a galaxy to suddenly become illuminated, such as supernova explosions or when stars come too close to black holes and destroy themselves during a phenomenon called tidal disruption events.

But such events last only tens or hundreds of days — and SDSS1335+0728’s brightness continues to increase more than four years after researchers first observed its brightness increase like the flip of a cosmic light switch.

And the variations in brightness in the galaxy are unlike anything astronomers have seen before, which only left them even more intrigued.

An unprecedented cosmic event

To find answers, the team consulted archival data from NASA’s Wide-field Infrared Survey Explorer and Galaxy Evolution Explorer, the Two Micron All Sky Survey, the Sloan Digital Sky Survey and other observatories.

The researchers compared the data with follow-up observations made by the European Southern Observatory’s Very Large Telescope, or VLT, in Chile, the Southern Astrophysical Research Telescope in Chile, the WM Keck Observatory in Hawaii, and NASA astronauts Neil Gehrels Swift and Chandra . X-ray observatories.

Together, the datasets presented a broad portrait of the galaxy before and after the December 2019 observation, revealing that the galaxy has switched to emitting much more ultraviolet, visible and infrared light in recent years, and X-rays starting in February – the which is unprecedented. behavior, said Sánchez Sáez.

Given that the galaxy is 300 million light-years away, the events astronomers are observing happened in the past — but light from these events is only now reaching Earth, after traveling through space for millions of years. One light year is distance that light travels in one yearwhat it is 5.88 trillion miles (9.46 trillion kilometers).

“The most tangible option to explain this phenomenon is that we are seeing how the (core) of the galaxy is starting to show (…) activity,” said study co-author Lorena Hernández García, an astronomer at the Millennium Institute of Astrophysics and the University of Valparaíso , both in Chile, in a statement. “If so, this would be the first time we have seen the activation of a massive black hole in real time.”

Sleeping celestial giants

Supermassive black holes are classified as having masses greater than 100,000 times that of our sun. They can be found at the center of most galaxies, including the Milky Way.

“These giant monsters are usually sleeping and not directly visible,” study co-author Claudio Ricci, an associate professor at Diego Portales University in Chile, said in a statement. “In the case of SDSS1335+0728, we were able to observe the awakening of the enormous black hole, (which) suddenly began to feast on the gas available in its surroundings, becoming very bright.”

Previous research has pointed to dormant galaxies that appear to become active after several years, which is usually triggered by the activity of a black hole, but the process of a black hole waking up has never been directly observed before, until now, Hernández García said. .

The same scenario could occur with Sagittarius A*, the supermassive black hole at the center of the Milky Way, but astronomers aren’t sure how likely it is to occur, Ricci said.

Astronomers cannot rule out that their observation could be an unusually slow tidal disruption event or a new unknown celestial phenomenon.

“Regardless of the nature of the variations, (this galaxy) provides valuable information about how black holes grow and evolve,” said Sánchez Sáez. “We hope that instruments like (MUSE on the VLT or those on the upcoming Extremely Large Telescope) will be fundamental to understanding (why the galaxy is glowing).”

For more news and newsletters from CNN, create an account at CNN.com